What Is Wrong With My Vigna?

Are there any tan to brown sunken lesions on leaves, lesions are merging to girdle stems and petioles?

Is there severe defoliation of plants, extensive lesions on stems and pods are apparent?

Are there any small, necrotic flecks on leaves that develop a chlorotic halo and expand into tan brown necrotic spots?

Are the seedlings dying and the stems are girdled or rotted at soil line?

Are the leaves covered with white powder?

Are the leaves curled and distorted?

Are the leaves covered in coarse stippling and may appear silvery?

Are there singular, or closely grouped circular to irregularly shaped holes in the foliage?

These symptoms indicate a fungal disease - Anthracnose. Avoid stressing plants by providing them with adequate irrigation and fertilization. Avoid damaging plants and creating wounds for pathogens to enter. Prune out dead or dying limbs to reduce levels of disease inoculum.

Asochyta blight is a fungal disease transmitted by infected seed and infected plant debris. Greasy, greenish-black, water-soaked spots appear on the lower leaves. Rainy or cloudy days with temperatures of 70-80 degrees F and nights at 40- 60 degrees F provide ideal conditions for the rapid growth of this fungus. Practice good garden hygiene at the end of the season and discard, do not compost, possibly diseased plants. Space plants to allow for adequate air circulation. Avoid overhead watering which may spread fungus spores.

Cercospora leaf blight is caused by a fungus that can be introduced through an infected seed and spread by wind or water splash. Plant only pathogen-free seed from a reputable nursery. Apply copper-based foliar fungicide if the disease emerges. Keep the area clean and be sure to dispose of plant debris.

If your seedlings are falling over and the stems are girdled or rotted at the soil line, the most likely cause is a damping-off disease. Remove and destroy all infected plants. To prevent damping-off let the soil surface dry between waterings, thin seedlings to avoid overcrowding, and do not add nitrogen fertilizers until plants have developed leaves.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. The appropriate fungicidal spray will protect your plant from further infections.

Distorted and curled leaves are caused by aphids. These tiny insects cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

These symptoms may indicate thrips. Thrips are tiny, yellow to black flying insects. Severely infected plant parts should be removed and destroyed. Control thrips by introducing lady beetles or lacewings, their natural predators. Insecticidal soap helps in severe infestations.

Armyworm is a known pest of vigna plants. This insect can go through 3–5 generations a year. Organic methods of controlling armyworms include biological control by natural enemies that parasitize the larvae and the application of BTK spray (Bacillus thuringiensis).

If the leaves have notched edges the culprits are Vine weevils. The wingless, black bugs are adults that feed on the leaves of many plant species. You can get rid of them by handpicking or by gently shaking the plant and collecting fallen beetles. Spray leaves several times with pyrethrin for major infestations.